Cr/SiO2 catalysts were prepared by impregnation of chromium acetate (1 and 3 wt.% Cr) and bis(triphenylsilyl)chromate (0.5 wt.% Cr) over commercial silica. These samples were analyzed by temperature programmed reduction (TPR) and infrared spectroscopy (FT-IR) of CO and C2H4 adsorbed in order to characterize the chromium species, mainly Cr2+ species distribution (Cr-A(2+), Cr-B(2+) and Cr-C(2+)) and polymerization aspects. The catalysts prepared with chromium acetate presented only Cr6+ after calcination, while the catalyst prepared with bis(triphenylsilyl)chromate presented Cr6+ and a fraction of Cr3+. After reduction with CO, the catalysts prepared with chromium acetate showed more Cr-B(2+) than Cr-A(2+) species. The distribution of Cr2+ species influenced the catalytic activity. The catalyst with 3 wt.% Cr from acetate presented the greatest amount of species Cr-A(2+) and Cr-B(2+) and the best polymerization activity. The behavior of isolated hydroxyls band during polymerization tests, characterized by FT-IR, suggests its participation in the reaction mechanism.